Self-adjusting propeller



Sept. 21 1926.

F, w. STODDER SELF ADJUSTING PROPELLER Filed Feb. 2, 1926 Patented Sept. 21, 1926.

FRANK W. STODDER, OF WEST SOMERVILLE, MASSACHUSETTS.

SELF-ADJUSTING PROPELLER.

Application filed February 2, 1926. Serial No. 85,550.

, My present invention is a novel and improved propeller, particularly adapted for use in turbines, and being self-adjusting for varying speeds or current velocities.

My present propeller is an improvement on that shown and described in my prior Patent No. 1,189,749, issued July 4, 1916, particularly in the adaptation which I have made of the present propeller for use as an impeller in a turbine runner.

A principal object of my invention is to provide a propeller which will maintain at all times the most efficient pitch irrespective of the speed, and which will be efficient at speeds of from fifteen percent to one hundred percent of the energizing current velocity.

A further important feature of the invention consists in positioning the propeller or impeller blades at right angles to a suitable hub and freely-swiveled in an arc of seventy-five degrees. To insure this limit of movement I preferably utilize stops limiting the swivel of the blades from a fifteen degree angle with the shaft to an angle of ninety degrees, havingthe back or convex surface of the blades opposed to the fluid current.

It will be appreciated that my novel propeller may be utilized not only as an impeller for a turbine runner, but also as a propeller for use in water or air, but the application of same to a turbine being one of the principal features, I will describe its application thereto more in detail.

While I have illustrated one preferred form of my invention in the accompanying drawing in connection with a two-bladed propeller, it will be appreciated that it 1s not intended to thus restrict the invention,

but I may utilize any desired number of blades, for greatest efficiency.

In the operation of my invention as applied to a turbine runner, when power is applied, the blades are carried to the fifteen degree stop, and when in that position impart initial revolution to the runner. As the speed of revolution of the runner increases, the source of energy as afleeting the runner will be at a constantly increased angle with the shaft because of the fact that the source of energy is a compromise of current velocity and the speed of the runner, and the blades will move, automatically, towards the ninety degree stop. The function of this ninety degree stop is to insure the blades being in a proper position to swing toward the fifteen degree stop when power is applied, instead of permitting loose play of the blades and consequent loss of energy. Thus the blades areat all times in position to be affected by the fluid current and impart rotation to the runner at the earliest possible instant.

As the blades are maintained constantly energy, they automatically adapt themselves to different loads or speeds of revolution, and since they are always at the most efficient pitch, milling of the current is minimized. Even when the runner has no load, it will not race, but will take an even high speed where the peripheral speed ofthe runner is much greater than the current velocity. Because of the constant drift resistanee of the blades there will be no pulsing or back-lash imparted to the current.

A further and important feature of my present invention consists in the fact that because the blades always have a pitch for maximum energy with a minimum of drift resistance, I am able to eliminate the customary guide vanes for deflecting the current against the blades, but by compounding, and having one runner with right-hand blades and another with left-hand blades and corresponding directions of rotation, the drift resistance to the current velocity is merely doubled, while there is a much greater increase in the power developed. By having the convex surface of the blades opposed to the fluid current, the greater surface of the blade is used for power purposes, while the concave side produces a desirable cavitation.

I have discovered that the formation of blade best adapted for the purposes desired, is to form each blade offset from the axis of swivel at a ratio of approximately one unit offset to five units trailing width'at any line at right angles to the plane of the cutting edge, and having at any radius from the center of the hub a uniform ratio of width to the speed of travel of the runin an angle to the plane of the source of.

ner in its revolution. This configuration of the blades is more clearly set forth in the accompanying drawings.

Further features of the invention, details of construction, and advantages, will be hereinafter more. fully pointed out and claimed. 1

Referring to the drawings, illustrating a pgreferred embodiment of my invention ig. 1 illustrates a turbine casing in crosssection with my novel propeller or impeller positioned therein;

Fig. 2 is a side elevation of the propeller, illustrating one method of swivelling blades in the hub;

Fig. 3 is a top plan view of the form shown in Fig. 2;

Fig. 4 is a front elevation thereof;

Fig. 5 being a cross-sectional 'view of the blade on the line 5-5 of Fig. 2; and

Fig. 6 is a cross-sectional view on the line 6-6 of Fig. 2.

In the drawings my novel impeller is illustrated as applied to a turbine casing 1, having a bearing 2 in the spider web bracing 3, and a second bearing 4. in the wall of the casing. Through these bearings extends a shaft 5, of any desired size or material, one end of this shaft being attached to a pulley, wheel or other driven device 6. The other end of the shaft 5 is preferably keyed to a hub comprising two sections 7 and 8, the shaft 5 being rotated by revolution of the hub. Freely swiveled' in the hub and at right an Ice to the axis of rotation thereof, are a pdurality of propeller or impeller blades 9, here illustrated as two in number, although it will be appreciated that I may utilize any desired number of blades and am not limited, to the number shown.

As shown in Fig. 2, the blades 9 are provided with suitable studs 10 having shoulders 11 which bear in appropriate recesses in the hub sections 7 and 8. These hub sections are united by bolts 12 and nuts 13 preferably positioned in recesses 14. When applying the blades to the hub, the shoulders 11 are fitted in their recesses and the two sections of the hub thus secured together, as explained, by the bolts 12 and nuts 13. The hub section 8 is provided with lugs or stops 15 to limit the movement of the swivel of the blades 9 to an angle of 15 with the shaft 5; the blades 9 being provided with. corners 16 to abut against these sto s 15. The hub section 7 has lugs or stops 1 against which the corners 16 abut to limit the swivel of the blades in the opposite direction to an angle of 90 with the shaft 5. It will thus be seen that the blades 9 are freely swiveled in an arc of 75 on the axis 18. Also, for the most efficient action of the blades 9, they are so constructed that their respective edges are in planes converging from the center of the hub, the center of the hub being indicated .at 19 and the planes'r'eferred to being shown at 18 and 20, the blades being thus movable about a common center.

Fig. 5 illustrates in cross-section the general form of the blade 9 on the line 5-5 of Fig. 2 and illustrates the concave face 21 as being coincident with the plane 22 from the center 19 of the hub.

Fig. 6 is a cross-sectional view on the line 6-6 of Fig. 2, and is similar to a view taken on the line ti -6 of Fig. 2, the only difference being in the trailing width of the blade, and the corresponding offset. This Figure 6 illustrates very clearly the important feature of having each blade offset from the axis of swivel at a ratio of approximately one unit offset to five units trailing width at any line at right angles to the plane of the cutting edge. In this figure the cut ting edge is indicated at 24 and the axis of swivel indicated at the point 23. A indicates the one unit offset from the axis of swivel at the point 23, and B indicates the five units trailing width of the blade.

This approximate proportioning is found 90,.

to be the most efiicient in operation, and it will be appreciated that while this illustration in Fig. 6 is taken on the line 6-6 of. Fig. 2, the same proportions will be present at any line at right angles to the plane 5 of the cutting edge.

The operation of my novel propeller or impeller willbe readily understood. The same being installed in a suitable turbine casing, such as 1, and fluid current, such as 1 water, steam, air or the like, applied, in the direction of the arrows 25, the blades 9 will be instantly carried to the 15 angle, as clearly illustrated in Figs. 1 and 3, and when in this position will impart initial revolution to the hub, shaft 5 and driven member 6. As the speed of revolution increases, the source of energy as affecting the runner will be at a greater and greater angle with the shaft due to the fact that said source of 1 energy is a compromise of current velocity and speed of runner, and blades move automatically towards the 90 angle, to which they are limited by the stops 17, as illustrated in dotted lines in Fig. 3. Since the blades 9 maintain a constant angle of reslstance to the source of energy, they will adapt themselves to different loads or speeds of revolution, and as they are always at their most will be minimized, with no back lash. The blades of my novel propeller are also so formed that they will have, at any radius from the center of the hub, a uniform ratio of width to speed of travel of the runner in its revolution, and I believe this feature is also new. i

The walls of the casing 1 are formed as shown at 26, to curve around the outer periphery of the blades 9 in their travel, and

eflicient pitch, milling of the current 2 thus allow a minimum of fluid to passoutside of the periphery of the blades in their revolution, thus directing practically the entire fluid force, current or power against the blades.

It will also be appreciated that I am not limited to a single hub and blades, as illustrated, but may utilize two more such runners, one having right hand blades, and one having left hand blades, etc., and therefore corresponding directions of rotation. In such construction the drift resistance to the current is only doubled, while there is a greater increase in the power developed, the

rst set of blades acting as guide vanes to deflect the .fluid current against the succeeding set of blades at the most eflicient angle or. pitch. I believe that such compounding of turbine runners, without the use of guide vanes to deflect the fluid current, is new, and I wish to claim this feature, in addition to the other features herein described, broadly.

It will also be appreciated that while I have primarily described myv present invention as applied to turbine runners, I am not limited thereto, but may utilize my novel propeller for use as a driving means, either 1n air or water, wherein the action would be reversed and power would be transmitted to the propeller by the object driven,-r ath"er than, as in the present case where ower is transmitted to the propeller by the ui'd current. Such application of my novel propeller is clearly within the province of the present invention, and I wish to include this feature in the present claims.

While I have necessarily described my invention somewhat in deta11,.it will be appreciated that I am not limited thereto, but may of the blade at any line at right angles to the plane of the cutting edge of the blade.

2. A propeller, having its blades pivotally mounted for free and independent swlvelling, each blade being offset from the axis of swivel at a ratio of approximately one unit ofl'set to five units trailing width of the blade at any line at right an les to the lane of the cuttin edge of the lade, and

aving at any ra ius from the center of the hub a uniform ratio of width to speed of travel of said propeller in its revolution.

3. A propeller, having its blades pivotally mounted for free and independent swivelling in an arc of seventy-five degrees, stops to limit the movement of said blades within said arc, each blade being olfset from the axis of swivel at a ratio of approximately one unit offset to five units trailing width of the blade at any line at right angles to the lane of the cuttin the blade, an havin at any ra ius from the center of the hu a uniform ratio of width to speed of travel of said propeller in its revolution.

In testimony whereof, -I have signed my name to this specification. 4

FRANK w. s'ronnnn edge of I 

